Metal muscles drive ‘robo-bat’ Micro Aerial Vehicle

The ‘robo-bat’ skeleton (Photo: Gheorghe Bunget, North Carolina State University)

Researchers are increasingly looking to nature for design inspiration in a wide range of mechanical devices. Doing so allows them to draw on the millions of years of evolution that have resulted in designs offering superior performance and efficiency. Micro Aerial Vehicles (MAVs) is one field that has recognized the maneuverability and performance virtue of nature’s small flyers, with various attempts being made to mimic these designs and produce vehicles that outperform traditional fixed-wing or rotary-wing craft. We’ve seen the development of a tiny a ‘nano air vehicle’ inspired by the hummingbird, a UAV based on a Pterodactyl and a six-inch long robotic spy plane that, like this new design from North Carolina University, draws on the physical characteristics of a bat.

Basing their design on the bat’s skeletal and muscular systems, researchers have constructed a fully assembled "robo-bat" skeleton that weighs less than six grams.

The team is now completing fabrication and assembly of the joints, muscular system and wing membrane for the robo-bat, which would allow it to fly with the same efficient flapping motion used by real bats. To mimic the function performed by many tiny bones, cartilage and tendons in real bats for the joints, the research team is using a shape-memory metal alloy that is super-elastic, provides a full range of motion, but will always return to its original position.

Smart materials are also being used for the muscular system explains researcher Dr. Stefan Seelecke: "We're using an alloy that responds to the heat from an electric current. That heat actuates micro-scale wires the size of a human hair, making them contract like 'metal muscles'. During the contraction, the powerful muscle wires also change their electric resistance, which can be easily measured, thus providing simultaneous action and sensory input. This dual functionality will help cut down on the robo-bat's weight, and allow the robot to respond quickly to changing conditions – such as a gust of wind – as perfectly as a real bat."

The researchers believe their robo-bat will be able to be effective for a wide range of uses, from indoor surveillance to exploring collapsed buildings and could help expand our understanding of aerodynamics.

Researcher Gheorghe Bunget will present the team’s findings this September at the American Society of Mechanical Engineers Conference on Smart Materials, Adaptive Structures and Intelligent Systems in Oxnard, California.